a. Field of Invention
This application pertains to an automatic apparatus and method for measuring a distance between two points. More specifically, in one embodiment, the distance is between two points is obtained from a remote location by measuring the distances from the remote location to each of the points, measuring a corresponding angle, and using these parameters to determine the distance therebetween.
b. Description of the Prior Art
It is frequently important to measure the distance between two points. For example, surveyors have a large number of tools and devices and disposal to measure the distances between landmarks, as well as their elevation and relative bearing.
Contractors and other professionals in the building industry often need to measure distances between various critical points as well. Traditionally this was accomplished by extending or laying down a measuring tape between the two points and reading the distance from the tape. If the tape was too short, or if there are obstacles between the points, then intermediate measurements are made along the path between the two points. Of course, this process is tedious and time-consuming. Moreover, in some instances, one or both points of interest are inaccessible and therefore the distance between them can be determined using indirect means or approximations.
Recently, the task of measuring devices has been eased somewhat by the availability of electronic measurement devices. These devices are now readily available and work by sending out an ultrasound, laser or other types of beams and determining the transit time required for the beam to reach the selected point, and return. One such device, called the Laser Dimension Master is made by Calculated Industries of Carson City, Nev. The device has a head rotatable between two perpendicular positions and generates an ultrasound beam for making measurements and a visible laser beam for aiming the device. While these devices are easy to use, most of them can still only measure the distance from the measuring device and a remote point and cannot be used from a remote location to measure the distance between two arbitrary points. One exception presently known are the laser measuring device made by Lasermeters of Edmond, Okla. (See Lasermeters.com). This company makes a line of devices under the name of Disto. A Disto device can be used to measure the distance between two points using three measurements. First, the device is directed at the first point and a measurement is taken. Next, the device is directed at an intermediate point disposed along a perpendicular line to the line between the two points and a second measurement is taken Finally, the device is directed at the second point and a third measurement is taken. The distances between the first point, the intermediate point, and the second point are determined using the Pythagorean Theorem, and then added. This approach has many problems which render it impractical for most applications. First, the user must determine by eye the location of the intermediate point. Obviously this process introduces a degree of uncertainty and inaccuracy. Second, in most instances, except in very special instances, the intermediate point does not even fall between the two points, in which case, the distances must be subtracted, not added.
In addition, devices of various complexities are known for measuring angles. Initially, these devices, including protractors, and the like, were strictly mechanical devices. In more recent times, electronic angle measuring devices have become available which can make the task of measuring angles easier and more accurate. One device is available from Bosch (Model No. DWM40L) However, these devices cannot be used to measure distance.